My girlfriend actually encourages me to jerk off when I get the urge, especially if she is around. Our sex drives are similar but I am just a tad more horny on average then she is, so masturbation is a good way to even us out. Before we go to bed (we're living together in sin

) I will usually pull out my dick and start tugging. Sometime she will end up getting so hot from it that she decides she is ready to go, other times she'll just say don't mess the sheets. Every once in a while she'll actually tell me what to do which I think is really hot, go faster/slow/when to cum etc. Once she made me stroke slowly for over an hour before letting me cum!